Nearly half of all Americans say Obama is not delivering on his major campaign promises, and a narrow majority have just some or no confidence that he will make the right decisions for the country's future.

More than a third see the president as falling short of their expectations, about double the proportion saying so at the 100-day mark of Obama's presidency in April. At the time, 63 percent said the president had accomplished a "great deal" or a "good amount." Now, the portion saying so has dropped to 47 percent.

Republicans are particularly critical of Obama's efforts in general and on big domestic and foreign issues. Just 20 percent of Republicans approve of his overall job performance, compared with 87 percent of Democrats. That partisan gap is bigger than any that Presidents Bill Clinton, George H.W. Bush or Ronald Reagan ever faced among the general public. It's about on par with divergent ratings of George W. Bush across his second term.

But Obama continues to benefit from GOP weak points. Three-quarters of all adults lack confidence in the Republicans in Congress to make good decisions for the future, and when it comes to assigning blame for the nation's economic woes, about twice as many fault the George W. Bush administration as do Obama's.

There is a growing racial divide in public assessments of Obama. African Americans overwhelmingly approve of the job he is doing, just as they did in April. There has also been little change in the numbers saying he has accomplished a lot so far. But among whites, a sense that Obama has achieved at least a good amount and his approval rating have both dropped nearly 20 points.

There has been a dramatic falloff in the percentage of whites saying that Obama has brought needed change to Washington. In April, 58 percent of whites said Obama had done this; now the number is 41 percent. Overall, 50 percent of all those polled say Obama has delivered the change that was a main theme of his candidacy; 49 percent say he has not.

At the 100-day mark, nearly two-thirds of independents said the president had brought change; in the new poll, fewer than half say so.

The poll was conducted by telephone Tuesday through Friday among a random national sample of 1,083 adults. The results for the full poll have a margin of sampling error of plus or minus three percentage points.